The present invention relates to damper valves and more particularly to an improved stack damper valve primarily for use in stack systems which operate at relatively high temperatures and function as tight shutoff block valves in either lined or unlined duct systems.
Previously stack systems employed valves of the butterfly type which basically comprise a single valve disc with a concentrically located shaft. This valve design does not provide tight shutoff due to the clearances required between the valve disc and stack lining or wall. These prior art valves have proved unsatisfactory, since they do not provide the desired tight shutoff characteristics and also cannot be used in both unlined and lined systems. Typical valves comprise those employed as ceiling diffusers for air conditioning or heater duct systems wherein the valves are primarily used to balance flow to the air conditioning and the heating duct systems. Other prior art valves can be found in U.S. Pat. Nos. 3,507,256, 2,020,686, and 3,181,527; however, they do not disclose the desireable seating and hinge pivot support of the present vlve and are not suitable for use both in a low temperature unlined stack and high temperature lined stock. Other less relevant patents located include U.S. Pat. Nos. 1,099,689, 3,084,715, 3,241,586, and 3,533,438.